I.—Geology of Weymouth, Portland, and Coast of Dorsetshire, From

Reviews—Damon's Geology of Weymouth. 511 IR, IE "V" I IE "W S.

GEOLOGY OF WEYMOUTH, PORTLAND, AND COAST OF DORSETSHIRE, FROM SWANAGE TO BRIDPORT-ON-THE-SEA : WITH NATURAL HlSTORY AND ARCHAEOLOGICAL NOTES. By ROBERT DAMON, F.G.S. pp. xii. and 250. New Edition. (Weymouth: E. F. Damon. London: Edward Stanford, 1884.) R. DAMON'S "Geology of Weymouth" has so long and so deservedly ranked as one of our best local geological guides, thaMt we heartily welcome this new edition, and more especially as nearly a quarter of a century has elapsed since its predecessor was published. While Geology has made immense strides during this period, yet it is a significant and happy fact that the names of the formations remain the same as those chronicled in 1860 ; and the student is not perplexed, as he may be in some other districts, by many con- tradictory opinions on the grouping of the rocks, nor (as a rule) by finding two or three names applied to the same formations by different individuals who have written about them. The chief additions to our knowledge of the geology of the neighbourhood of Weymouth, consist in enlarged lists of the fossils, and many more particulars about the rocks. The labours of Messrs. Blake and Hudleston on the Corallian Rocks call for special mention, as, although they made seven divisions in this group at Weymouth, which would on first thoughts seem a burden to the science, yet these divisions are locally well marked, and their names are very useful in the district for those who study the beds in detail, and collect fossils from definite horizons. Mr. Damon has introduced a neat photograph showing a block of rock containing 60 or 70 specimens of Trigonia clavellata from the " Trigonia-beds" of the Coral Rag at Weymouth, which may well astonish the ordinary observer. The shore in places at Osmington and south of Weymouth is truly paved with Trigonias—but, alas! really good specimens are not readily to be obtained. And it is only by the use of the chisel and much patience that such a number of beautiful specimens could have been developed. Nevertheless the collector is likely to be well rewarded in what- soever direction he can wander from Weymouth. The bank of Fuller's Earth almost made up of specimens of Ostrea acuminata, discovered by Mr. Damon at Langton Herring, the many quarries in Forest Marble and Coinbrash, the cliffs of Oxford Clay, Coral Rag and Kimmeridge Clay, and again the interesting Isle of Portland, with its stone-quarries and Purbeck Dirt-bed, are all within easy distance of Weymouth. Then, too, steamers will convey the visitor to the romantic cove of Lulworth, with its contorted Purbeck strata, and here the Chalk, Greensand and Wealden Beds may be profitably studied. Further along the coast we pass sections of similar rocks in the picturesque cliffs of Warbarrow, and Mr. Damon conducts us to these, passing thence by Gad Cliff to the dark shales of Kimmeridge,

Downloaded from https:/www.cambridge.org/core. Newcastle University, on 20 Feb 2017 at 00:26:13, subject to the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S0016756800186005 512 Reviews—Damon's Geology of Weymouth. and round Durlston Head to the famous stone-district of Swanaga. Here he aids us by inserting in full the detailed section of the Purbeck strata of Durlston Bay, measured many years ago by Mr. H. W. Bristow. Our guide takes us also to the Punfield Beds, and beyond the great Chalk ridge on which Corfe Castle stands, to the Tertiary tracts, and the pipe-clays and leaf-beds developed to the north of Corfe and near Bournemouth. Glancing back at some of the new facts presented to our notice, we may especially mention a number of minute mollnsca, not previously found in this country, which were obtained by Mr. Damon in the Upper Portland rocks at Portland. The species have been described from similar rocks at Boulogne by MM. de Loriol and Pellat, and they belong to the genera Cerithium, Delphinnla, Nerita, Odostomia, etc. Mr. Damon makes some interesting remarks on the great Purbeck Dirt-bed, comparing it with the Tchornozem or " Black Earth " of Central Eussia, which by some authorities is supposed to be the decomposed debris of an ancient forest. Having brought from Eussia samples of this famous earth, which produces some of the richest soil in Eussia, both for corn and grass, Mr. Damon, by experiment, proved that it exceeded in fertility both garden mould, and the old soil of the Purbeck Beds. The Quaternary deposits are fully described, and passing on to the times that perhaps are scarcely geological, Mr. Damon draws attention to the most interesting discovery of some underground huts or Dene-holes of beehive-form, that were uncovered in Portland in removing the Purbeck strata ("rubble," "hard slate," etc.), from the merchantable Portland Stone that lies below. That these struc- tures were in part used as ancient granaries appears highly probable. We should mention that Mr. Damon extends his account of the strata westwards as far as Bridport Harbour and Eype, a district famed for its fossils, especially those of the " Dorsetshire Cephalopoda- bed." The exact age of this bed is, by-the-bye, a matter of some controversy—perhaps we should say the exact palseontological equivalent, for its stratigraphical position is clear enough. Strictly speaking, the whole of the Inferior Oolite in the district is a Cepha- lopoda-bed. Mr. Etheridge has furnished a detailed section of the Inferior Oolite Limestone and Sands near Bridport Harbour, and although he would correlate the beds rather differently than does Professor Buckman, yet probably this divergence of opinion will not affect the enthusiasm of collectors, who may be well content to label their fossils as from the Inferior Oolite, without disturbing their minds about the question of zones and minor subdivisions. To these, the list of the more abundant fossils from the Inferior Oolite of Bridport and Burton Bradstock will doubtless prove most serviceable. There is also a useful list of fossils from the Fuller's Earth of West Cliff, Bridport Harbour. While woodcuts of many fossils are given in this book, it may be noted that a new edition of the supplement or atlas to the work was

issued in 1880, and that contains eighteen beautiful lithographic plates of fossils from the Oolites, with descriptions of several new species. The map accompanying this volume has been executed by Mr. Stanford with his unrivalled clearness and excellence of style, though perhaps the faults are marked a little too clearly. The geology is reduced from the Geological Survey Map constructed by Mr. Bristow, and takes in the whole of the country from Swanage to Bridport Harbour. With this volume and its supplement the student will find himself well able to master the geology of this interesting and picturesque district; for Mr. Damon furnishes many miscellaneous geological notes and also gives references to papers where further details may be found, while his memoranda on the Natural History and the Antiquities of the county will lend much additional charm to its study, and perhaps stimulate enquiry into other branches of science besides geology.

ABSTRACTS OP PAPERS READ BEFORE THE GEOLOGICAL SECTION OF THE BRITISH ASSOCIATION AT MONTREAL, AUGUST, 1884. (Continued from the October Number, p. 478.) 13.—WHAT IS A MINERAL VEIN OR LODE? By C. LE NEVE FOSTER, B.A., D.Sc, F.G.S., H.M. Inspector of Mines. f"pHE author quoted briefly the definitions of a mineral vein given I by Werner, Came, Von Cotta, Grimm, Von Groddeck, Geikie, Sandberger, and Serlo, who, in common with most geologists, have looked upon mineral veins as ' the contents of fissures.' While admitting that a very large number of veins may be so described, the author contended that the exceptions are sufficiently important and numerous to warrant a change in the definition. He is of opinion that many of the principal and most productive tin-lodes in Cornwall are simply tabular masses of altered granite adjacent to fissures; and he brought forward the opinions of other geologists to show that certain veins in the English Lake district, the Tyrol, Nova Scotia, Nevada, Colorado, California, and Australia are not filled-up fissures. In conclusion, he proposed the following definition : ' A mineral vein or lode is a tabular mineral mass formed, more or less entirely, subsequently to the enclosing rocks.'

14.—ON ICE-AGE THEORIES. By the Eev. E. HILL, M.A., F.G.S., Tutor of St. John's College, Cambridge. N the Montreal Mountain, in the neighbouring quarries, at the O mouth of the Saguenay River, and more or less everywhere over all Canada and all the north and north-west of this continent, are seen phenonema which imply a former vastly extended action of ice. The like are found over Europe and Asia, thus completely encircling the pole. Many theories have been propounded to account for these facts. It is proposed to pass these before you in review. DECADE III. TOL. I.—NO. XI. 33